The present invention relates to the preparation of expanded pressure welded passageway panels. More particularly, the present invention relates to the preparation of metal panels of the foregoing type having utility in heat exchange applications wherein the heat exchange medium is circulated through the passageways.
A commonly used and efficient type of heat exchange unit for a variety of purposes is formed from a plurality of superimposed sheets of metal having internally disposed therebetween one or more conduits or tubes to carry a heat exchange medium. According to one known method of manufacture, as illustrated in U.S. Pat. No. 2,690,002, this type of heat exchange unit may be readily manufactured to provide if desired a great multiplicity of tubes in a metal panel in virtually any desired pattern. This method involves the application of a suitable predetermined pattern of weld inhibiting material corresponding to desired passageways in the final article between component sheets and pressure welding all adjoining areas except those separated by the weld inhibiting material. This forms a unified composite panel which is subsequently inflated along the unwelded areas to erect tubes integral with the resultant panel.
The sheet-like structure having internal hollow passageways formed in accordance with the foregoing process is well adapted for use as a heat exchanger wherein a heat exchange medium can be circulated throughout the structure in the internal passageways. The panel may naturally be provided with the necessary connections for the circulation of the heat exchange medium. As can be appreciated, these connections can vary in number and displacement to suit the desired end use of the heat exchange panel. For example, U.S. Pat. No. 2,822,151, issued Feb. 4, 1958, discloses a plate-like heat exchanger of the foregoing type provided with a single connection for both entry and exit of fluid, and possesses particular utility for the circulation of refrigerants. Correspondingly, copending application Ser. No. 573,953, the disclosure of which is incorporated herein by reference, illustrates a heat exchange structure of the foregoing type provided with longitudinally opposed connections comprising, respectively, inlet and outlet portions provided to enable the continuous flow of heat exchange medium transporting absorbed energy.
Heat exchanger panels of the foregoing type have found considerable utility in solar energy recovery systems. It is desirable, however, to provide improved panels similar to those discussed above and methods for obtaining same particularly for use in solar energy recovery systems. Thus, for example, panels formed by the foregoing process are frequently made of aluminum. Corrosion problems in these aluminum panels require the use of an inhibited heat transfer fluid to provide satisfactory life. Aluminum panels also require special connection procedures and special skills of installation. Panels made entirely of copper or copper alloys overcome these problems, but suffer from the disadvantage of considerably increased cost.
Another process used to make satisfactory panels for solar energy recovery systems involves the use of copper tubing soldered to flat copper plates. The cost of both materials and fabrication is high for such panels.
Accordingly, it is a principal object of the present invention to provide an improved method for the manufacture of hollow articles useful as heat exchangers, particularly in solar energy recovery systems, and also an improved panel obtained thereby.
It is a further object of the present invention to provide an improved method and panel as aforesaid which is inexpensive to prepare and which may be readily used with a variety of different metals.
Further objects and advantages of the present invention will appear hereinafter.